Opsonization and Phagocytosis

Question 1

opsonization

Answer 1

process of attaching opsonins to microbial surfaces to target microbes for opsonization

Question 2

osponins

Answer 2

macromolecules attached to surface of microbe, by neutrophls and macrophages

Question 3

specific opsonins

Answer 3

1. IgG

2. complement facotr C3

Question 4

what is required for most microbes to be phagocytized?

Answer 4

opsonization

Question 5

how does opsonization increase ingestion (via phagocytosis) of microbes?

Answer 5

it changes the hydrophilic cell surface to be more hydrophobic

Question 6

Steps of IgG mediated opsonization

Answer 6

1. binding of opsonized microbe to Fc receptors of phagocyte
2. Fc receptors activate phagocyte
3. phagocytosis of microbe
4. killing of ingested microbe

Question 7

steps of complement fragment mediated opsonization

Answer 7

1. C3b binds to microbe
2. recognition of bound C3b by phagocyte C3b receptor
3. phagocytosis

Question 8

what is a major benefit of opsonization?

Answer 8

focuses attack on microbes

Question 9

(naming Fc receptors. example being FCγRIII)

what does Fc mean?

Answer 9

receptor will bind to Fc portion of the antibody

Question 10

(naming Fc receptors. example being FCγRIII)

what does γ mean?

Answer 10

IgG is binding

Question 11

(naming Fc receptors. example being FCγRIII)

what does R mean?

Answer 11

receptor

Question 12

(naming Fc receptors. example being FCγRIII)

what does III mean?

Answer 12

third subtype

Question 13

(naming Fc receptors)

what does ε mean?

Answer 13

IgE is binding

Question 14

(naming Fc receptors)

what does α mean?

Answer 14

IgA is binding

Question 15

how many types of IgG receptors are in people?

Answer 15

3

Question 16

what is the most important IgG receptor for phagocytosis of IgG coated particles?

Answer 16

FCγRIII

R2 is key

Question 17

how many types of complement related proteins?

Answer 17

4

Question 18

what are the chemotactic factors of complement related proteins?

Answer 18

C3a and C5a

Question 19

what are the main complement derived opsonins of complement related proteins?

Answer 19

C3b and C3bi

Question 20

neutrophils

Answer 20

major phagocytic cell in innate response

Question 21

what is responsible for neutrophils’ killing abilities?

Answer 21

granules in cytoplasm

Question 22

what is released when neutrophils die?

Answer 22

CD16 (causes them to be marked by opsonins and cleared out)

Question 23

monocytes/macrophages

Answer 23

phagocytize and produce cytokines

Question 24

where are monocytes/macrophages found?

Answer 24

circulate in blood and move into tissue eventually

Question 25

what are the two mechanisms of killing?

Answer 25

1. oxidative (ROS) | 2. non-oxidative (pH change/enzymes)

Question 26

what are pathogen tactics to avoid being killed?

Answer 26

1. cytotoxicity to host cells 2. inhibit opsonization/ inactivate phagocytosis 3. survive intracellular killing (inhibit, escape or survive lysosomes)